Low molecular weight polyethylene polyamines are used in a wide variety of applications such as corrosion inhibitors, fabric softeners, lubricating oil additives, fungicides and many others. Despite the utility of polyethylene polyamines, they are currently obtained only as by-products of ethylenediamine manufactured by the reaction of ethylene dichloride with excess ammonia. Since the polyamines are by-products of ethylenediamine preparation, the supply and quality of available polyethylene polyamines are often variable. Generally, high yields of cyclic polyethylene polyamines, e.g., piperazine, aminoethylpiperazine and the like, are produced although it is the noncyclic polyamines such as diethylenetriamine, linear and branched triethylenetetramine and higher homologs that are commercially desirable. Moreover, since sodium chloride is co-produced in large quantities, separation of the products from the sodium chloride and the handling and disposal of this corrosive inorganic salt require special measures.
The prior art discloses various attempts to circumvent these difficulties and to provide controllable efficient routes to polyethylene polyamines:
U.S. Pat. No. 3,714,259 discloses the preparation of linear polyethylene amines by contacting ethanolamine with ethylenediamine compound in the presence of hydrogen and a hydrogenation catalyst. An example of a hydrogenation catalyst is nickel containing copper and chromium components. Significant amounts of water are included in the feedstock, namely 25-50 wt % based on the combined starting ethylenediamine and monoethanolamine.
U.S. Pat. No. 3,766,184 discloses the reductive amination of monoethanolamine by a metallic catalyst of iron and nickel and/or cobalt in the presence of hydrogen.
U.S. Pat. No. 4,036,881 discloses the preparation of polyalkylene polyamines by reacting an alkanolamine with an alkyleneamine compound in the presence of a phosphorus containing substance selected from the group consisting of acidic metal phosphates, phosphoric acid compounds and anhydrides and the phosphate esters.
U.S. Pat. No. 4,044,053 is somewhat similar to the '881 patent except that the alkyleneamine compound is present in an excess amount and a diol is used in place of the alkanolamine.
U.S. Pat. No. 4,314,083 discloses a process for selectively preparing predominantly noncyclic polyalkylene polyamines by reacting an alkanolamine with an alkyleneamine compound in the presence of a salt of a nitrogen or sulfur containing substance or the corresponding acid.
U.S. Pat. No. 4,324,917 discloses ion exchange resins containing phosphonic acid functionality as catalysts for the production of polyethylene polyamines by alkylation of alkyleneamines such as ethylenediamine with alkanolamines such as monoethanolamine.
It can be seen that the prior art requires a source of preformed ethylenediamine for reaction with monoethanolamine to produce polyethylene amines. There must be a sufficient quantity of ethylenediamine present initially in the reaction mixture or a sufficient quantity continuously added to the reaction mixture in the prior art processes. Thus, production of polyethylene amines requires preparation of substantial quantities of both monoethanolamine, the alkylating agent, and ethylenediamine, the aminating agent, in separate steps and subsequent co-polymerization of the monomers to provide polyethylene polyamines. Prior art routes to polyethylene polyamines are therefore limited by their dependence on a sufficient supply of preformed ethylenediamine compared to monoethanolamine in the reactions.